Switchboard circuits and apparatus for telephones.



H. J ROBERTS.

I I" SWITGHBOARD CIRCUITS AND APPARATUS FOR TELEPHONES.

' APPLICATION FILED SEPT. 5, 1905.

2 SHEETS-SHEET 1.

Patented Nov. 4, 1913.

fitorn e H. .LROBERTS. SWITGHBOARD cmcurrs AND APPARATUS FOR TBLBPHONES.

APPLICATION FILED SEPT. 5, 1905. I 7 1,077,? 53. Patented! Nov. 4, 1913.

2 SHBETSSHEET 2.

nnrrn s'rArns PATENT rrro.

HOMER J. ROBERTS, 0F EVANSTON, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO HOMER ROBERTS TELEPHONE 60., A CORPORATION OF WEST VIRGINIA.

SWITGHBOARD CIRCUITS AND APPARATUS FOR TELEPHONES.

To all whom it may concern.

Be it known that I, HOMER J. ROBERTS, a citizen of the United States, residing at Evanston, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Switchboard Circuits and Apparatus for Telephones, of which the following is a specification.

This invention relates to improvements in switchboard circuits and apparatus for telephones and it has for its general object the production of a system suitable for switchboards handling both selective party-lines and individual lines.

More specifically some of the salient objects of the invention may be stated as follows: To provide a system in which any number of pairs of cords may be arranged for use indiiferently with either selective call party-lines or individual lines; to pro vide a system wherein all of the cord-controlling keys pertaining to a particular group are placed under the direct control of a master-key which effects the conversion or specialization of cord keys for-the time being so that they may be used for connections with the selective party-lines; to provide a system which is susceptible of being installed in ordinary manual exchange switchboards without to a serious extent disturbing the switchboard connections already installed; to provide a system which enables a specialized form of electric current (for example, direct pulsating current) to be availed of for effecting the operation of the selective party-lines while not interfering with the use of ordinary ringing current for calling on individual lines; to provide between certain parts of the master-key peculiar mechanical and electrical connections which serve to effect certain novel results; to provide certain circuit connections and controlling mechanism therefor peculiar to a selective party-line system heretofore invented by me, and in general to provide improvements for the construction and arrangement of the system of the character referred to.

To the above ends the invention consists in the matters hereinafter described and more particularly pointed out in the appended claims.

The invention will be readily understood from the following description, reference Specification of Letters Patent.

Application filed September 5, 1905.

Patented Nov. 4, 1913.

Serial No. 276,975.

being had to the accompanying drawings forming a part thereof, in which Flgures 1 and 1 taken together represent diagrammatically the complete switchboard circuits and operating mechanism.

In the particular embodiment of the invention illustrated, it is designed for use in a switchboard which has both selective party-line subscribers and individual line subscribers; the selective party-lines being of that type in which the selections are performed by counting out a definite number of impulses of current of one polarity and the ringing of the several parties effected by throwing onto the line pulsating current of a polarity opposite that employed in se lecting.

In the present system two sets of signaling apparatus are embodied, one controlling the line drops and operated by common battery, the other controlling self-restoring supervisory signals and also operated by common battery. The supervisory signals are individual to the several pairs of cords so that they are severally in use only as their corresponding cords are in use.

In practice, in adding to an ordinary man ual exchange switchboard already installed selective party-lines, the cord keys already installed may be and usually are utilized by simply adding additional pairs of contact strips and additional bus-lines connecting each of the cord keys so converted to the master-key set. Thus arranged, the operator desiring to use any given pair of cords for connecting between two party-lines, or between one party-line and an individual line, simply places the key controlling that pair of cords in its self retaining position and thereafter performs the further work of completing the connections through the master-key, as well as the operation (which is usually necessary in lock-out party-line systems) of clearing, i. e. restoring the line to normal.

Referring now to the diagram, A, A, A designate a plurality of cord keys, and B, 13, two somewhat similar keys which latter together constitute the complete mastenkey set. C designates diagrammatically a source of usual alternating calling current, the generator shown being connected by bus-lines l and 2 with the several cord keys.

D designates as a whole diagrammatically a generator so arranged as to aflord pulsations of either polarity.

E designates as a whole an automatic pulsationcounter, which for convenience of description will be herein termed a selector; its function being to count out a definite number of pulsations and in this manner effect selection of the particular party wanted on a party-line.

F designates a main battery, which affords current for various purposes, and G a second battery of a less number of elements which supplies current for both signaling systems.

H, H, H designate a plurality of springjacks forming the terminals of corresponding metallic lines, and I, I, 1 corresponding line drops.

Each cord key is provided on each side with inner pairs of contacts, as 3, 3, 4e, 4: and 5, 5 and 6, (3, which, in the intermediate position of the key, are closed. The springs 3, l, 5 and 6 are respectively connected with the tip and sleeve sides of the cords, as 7, 8, 9 and 10, and are shifted into contact with outer springs 11, 12, 13 and 14, respectively, when the key is shifted in one direction or the other. Of these latter springs, 11 and 12 are connected with the bus-lines 1 and 2, respectively, while the springs 13 and 14: are connected with another pair of bus-lines 15 and 16, respectively. These latter lines lead to the master-key and, as will be seen by tracing the circuit, connect the master-key with the answering cord sides of the several keys A, A, A

The additional springs which are added to each key are indicated at 17, 18 and 19,20, respectively; the moving members 18 and 19 being connected with but insulated from the corresponding springs 13 and 14. Springs 18 and 19 are respectively connected with the left and right sides of another pair of bus-lines 21, 22, while the cooperating springs 17 and 20 are respectively connected with the innermost springs 3', 4' of the opposite side of the key and also with the innermost springs 5, 6 of the same side of the key. A condenser 28 is interposed in the connection leading from spring 17 to spring 5, z. e. from the tip side, for a purpose which will hereinafter appear. The connections of each key A, A, A are pre cisely similar.

Referring to the master-key set, the key B is so organized that when shifted in one direction (downwardly, as shown) it throws current through the selector E and to the answering cord of whatever cord key is in use and shifted to a self retaining position. Similarly when key B is shifted in the opposite direction it throws current through the selector E to. the connecting cord of the same cord key. In either of the shifted po sitions of key 13 the current sent to line may be pulsating positive or pulsating negative, depending upon the position of the selector E. That is to say, the selector E when rotating sends current of one polarity to line but as it reaches its normal or zero position it reverses the connections and sends current of opposite polarity to line. It will be seen from the foregoing that key B is utilized for calling the subscribers.

Connected with key B so as to move positively in both directions with the latter is a subsidiary key 13 which is so constructed as to shift the springs controlled thereby whenever it moves in either direction. This key performs various functions as will hereinafter appear, chief among which being the control of the battery con nections.

Key B is so organized as to place the main battery E which is of relatively large capacity directly to the lefthand side of the line and at the same time to ground at the opposite side of the battery; the shifting of the key in one direction (clownwardly, as shown) serving to throw the main battery direct to the answering cord and the shifting of the key in the opposite direction sending the current to the connecting cord. Connected with key B is a subsidiary key 13 similar to the subsidiary key B but so connected that it moves with key B in one direction only, namely when the latter key is shifted upwardly. The mechanical connection whereby this is effected is indicated at 24 wherein the stem of key 13 telescopes within a sleeve connected with key B; the end of the stem of key 13 terminating in proximity to the body of key 13. Key 13 is provided with a stem and push button whereby it may be depressed and when so depressed it obviously forces with it key B. The functions of key B are in general similar to those of key B. An auxiliary push button J is provided which is mounted on one end of a lever pivoted at 25, the opposite end of the lever being operatively connected with the stem of key member B". The push button J controls a group of contacts which throw pulsating current of one polarity from the generator D direct to the line through the answering cord. In the particular party-line system for which the present invention is in this instance specifically adapted, any subscriber who calls in is located and connection given him by locking out all stations between his set and Central, and this locking out is effected by operating the relays at the several stations one after another by a series of pulsations thrown to line through push button J.,

Since this operation is in effect running down the line until the station is reached from which the subscriber has called, the push button J will be designated the running key.

Git

A call for connection coming in over a subscribers party-line would throw the line drop, as for example at I, whereupon the operator would insert a plug of any available answering cord and secure talking connections and take the order from the calling subscriber as follows: Observing that the call was on a party-line she would shift the cord key to its self retaining position, thus extending the circuits from the spring jack over conductors 9, 5 and 13 to bus-line 15 and over conductors 10, 6 and 14 to bus-line 16, thereby extending the connections to the master-key set. Bus-lines 15 and 16 are connected with the master-key set through conductors 26 and 27, and the circuit closed by the running key in responding to the subscribers call may be traced as follows: Over line 26 to intermediate spring 28 of key B, inner spring .19, conductor 30 to intermediate spring 31 of running key, to back spring 32, thence over conductor 33 to conductor 34, from the latter over conductor 35 to the generator D, from the generator over conductor 36 to front spring 37 of the selector, thence to the intermediate spring 38, from the latter over conductor 39 to a contact arm 40, thence over conductor 41 to conductor 34" which connects by con-' ductor 42 with the back'contact 32 of the running key, which is at this time closed with intermediate spring 31. The latter, as hereinbefore described, is connected with conductor 27. This completes the circuit.

The result of throwing pulsations of one polarity over the circuit described is to lock out the subscribers successively until the subscriber is reached who called for the connection. By operating his switch hook or some other suitable act the subscriber'places his set in such condition that succeeding impulses, after his instrument has been reached, will fail to pass the same. But although he thus arrests the further selection it is necessary to put one or more impulses of opposite polarity through his set in order to place the same in talking circuit; This reverse polaritv impulse is sent over the line by shifting key B downwardly, which results in transposing the connections between the generator D and the line. This reverse is not made until an ample number of impulses have been sent out to more than reach the substation; the excess impulses being ineffectual. That part of the circuit which is reversed may be traced from the generator over the conductor 35 to line 34, thence to outer spring 43 of key B, thence to switch spring 44, over conductor 45 to inner spring 46 of the running key, to switch spring 31, thence over line 27 to bus-line 16, which is connected through the cord key to the sleeve side of the line. From the other side of the generator the circuit is over conductor 36, springs 37 and 38,

conductor 39, arm 40, conductor 41 to spring 43 of key B, thence to switch spring 44 and thence to inner spring 46 of the running key over conductor 45. From spring 46 the circuit is through spring 31, thence over conductor 30 to and through springs 29 and '28 of key B and to bus-line 15 over conductor 26.

In the self-retaining position of the cord keys the exchange operators set, is in listesting connection with both ends of the cord. The listening connections with the answering end of the cord may be traced from bus-lines 15 and 16 as follows: Over conductor 26, springs 28, 29, conductor 30, springs 31 and 46 of the running key, conductor 45', springs 44 and an inner spring 48 of key B, through a condenser 49, thence over-a conductor 50 to the tip side of operators jack 51. The other side is over con- 7 ductor 27,springs 31 and 46 of the running key, conductor 45 to switch spring 44 and inner spring 48, thence through condenser 49 and over conductor 50 to spring 52 of key B, to spring 53 and back over conductor 54 to the sleeve side of the operators jack.

The listening circuit connections with the calling end of the cord are from bus-line 21 over a conductor 55, to switch spring 56 of key B, to inner spring 57, thence over conductor 58 to switch spring 59 of key B, thence to inner spring 60, and thence over conductor 61 to conductor 50 and to the tip side of the jack. Similarly from bus-line 22 over conductor 62 to switch spring 59, inner spring 60, conductor 50 and thence to the sleeve side of the jack as before traced.

The operator, having answered the subscriber, takes his order for a connection. If ya party on an individual line were wanted the connections would be made by simply inserting the connecting or calling end of the cord in the proper jack and shifting the cord key into its reversed. position, thereby throwing ringing circuit from the bus-lines 1 and 2 through the called subscribers bell. If, however, a party-line connection is called for, the next operation will be to insert the connecting end! of the cord in the proper jack and select and call the particular part-y wanted. The first operation, after inserting the plug, will be to set the selector dial to throw upon the line as many impulses (which are automatically counted out by the selector instrument) as will effect the selection of the right party. The selector E is so constructed that the dial and connected ratchet are spring-returned to the Zero position, and the returning movement iscontrolled by a magnet K the armature 7c of which constitutes an escapement lever. By means of a suitable handle the dial is manually turned forwardly as many notches as will correspond with the number of the party wanted counting the sub-stations outwardly from Central. The magnet escapement permits the dial to return one notch for each impulse, and as the dial reaches the zero position it is arrested by a stop-pin 68 engaging a suitable stationary stop 64:. Cams 65 and 66 are mounted upon the ends of the respective switch springs 38 and 38 of the selector, and these cams in the zero posit-ion of the dial rest in recesses 67, 67, respectively formed in an insulated hub 68 carried on the shaft of the selector and rotating with the ratchet of the latter. As soon as the dial is moved away from the zero position these cams are forced out of the V-shaped recesses and thereafter ride upon the periphery of the hub, thus moving the switch springs 38 and 38 outwardly into bearing with back contact springs 69 and 70, respectively. The shifting of the switch springs in this manner reverses the connections with the generator D, so that while selecting impulses are sent to line during the return of the selector to zero, when the selector reaches zero impulses of opposite polarity or ringing current is sent to line. Pressing the key B upwardly shifts its switch springs 59 and 59 outwardly into contact with outer springs 71 and 71, and these springs are connected with conductors 34 and 84, respectively, so that impulses are sent to line in substantially the same manner as when operating the running key.

A local circuit is closed through and operates the magnet K when the key B is closed in either direct-ion, (provided the selector has been set) which current may be traced as follows: From the generator through conductor 36 and spring 38 to back contact 70, thence over a conductor 72 to and through the magnet K, thence to a switch spring 73 pertaining to key B", from the latter to cooperating spring 74, which spring is connected with conductors 34 and 35, which lead back to the opposite side of the generator.

In the present invention a system of supervisory signals is provided which notifies the exchange operator whenever either party has ceased talking and hung up his receiver, thus indicating that the line should be cleared. The subscribers set is so organized that hanging up the receiver closes a full metallic bridge at his station; it being understood that the talking circuit at the subscribers station is through a condenser so that battery cannot flow. Describing this supervisory system, 75 designates a bus-line, and between this bus-line and the answering end of each cord is interposed a self-restoring signal 76; the conductors 77 in which these signals are interposed being connected with the sleeve side of the respective answering ends of the cords. Line 75 extends to and is connected with switch spring 78 of key B.

' This spring normally engages inner spring up his receiver, the self-restoring signal 76, :PQItiLlIlll'lg to the cord 1n use, is energized and indicates the line should be clear. At this point it may be explained that the line drops are operated by the battery G at Central and that said operation is efiected by grounding the line at the subscribers station. Ordinarily a flash-ground effected during the upward movement of the switch hook is employed to throw the line drop. The connection from line 84 through the battery G to ground is over conductor 83, spring 82, switch spring 73, a conductor 85 to an inner spring 86 controlled by key 13, from the latter to switch spring 7 8 of that key, thence by conductor 87 to a conductor 88 which connects the two switch springs 56 and 28 of key B with each other and to ground at 89 over a conductor 90.

Inasmuch as those subscribers between Central and the party selected are locked out in the act of selecting the latter, it follows that means must be provided for clearmg or restoring the look-out instruments to normal. As much of the subscribers circuit as is necessary to understand this operation is shown at L and M at the foot of Fig. 1; the party-line being shown connected with the spring jack H.

The clearing of the lines is effected by closing a ground-to-ground circuit from Central at one end through the main battery at Central, over the left or tip side of the subscribers line through the several clearing relays which are in series with said left line and to ground at the last subscribers set. At theremote end of the lefthand line is located a circuit-catching instrument N comprising a condenser 100, a magnet 101 in series with the condenser and connected to ground at 102, and a shunt conductor 103 which leads around the condenser to an armature104 which, when in closed position, engages a contact 105 connected with a few of the coils of the main magnet in such manner as to form a self-retaining circuit. I

It is necessary to clear both the calling and called subscribers if both are partylines, and the key B is so constituted as to effect clearing of the answering end of the cord when shifted downwardly, and the connecting or calling end when shifted in the reverse direction.

Assuming the calling subscribers line is to be cleared, the circuit will be from ground at 89 to switch spring 28, back spring 91, conductors 92 and 98 to battery F, thence by conductors 94 and 95 to back spring 91 and switch spring 28, which latter is connected by conductor 26 with the busline 15. Line 15 is connected with the tip side of the answering end of the cord through springs 18, 5, and conductor 9. In case the called subscribers line is to be cleared, the circuit will be from ground at Central through the battery over conductors 90 and 88, to switch spring 56, thence to back spring 96, to conductors 92 and 98 to battery, from battery over conductor 9a to 95, and to back spring 96, thence to switch spring 56 and from the latter to bus-line 21 over conductor 55. Bus line 21 is connected with spring 18 and engages spring 17 which is connected by a conductor 3 with the inner spring 3 of the cord key. Spring 3 is at this time closed with spring 3 which is connected by conductor 7 with the tip side of the plug.

In the operation of the master-key set, it is necessary that ground be cut off at Central when ringing impulses are sent to line; it is necessary that the supervisory signal and line drop circuits be protected against the main battery and generator D when clearing and ringing and it is desirable that the exchange operators set be either short circuited or opened before either the main battery or generator D circuits are thrown upon the line, in order to prevent reports in the operators ear. It is the function of the supervisory keys 13 and B to effect these results. In case the running key J is depressed, the ground at 89 is opened bet-ween the springs 78' and 86 of key 13, and in case the key B be shifted in an upwardly direction those same contact springs cut off the main battery F from the conductor 85 which is a part of the line drop circuit. In a similar manner move ment of key 13 opens the circuit between springs 7 8 and 79 which form part of the supervisory circuit. For the same reasons and in the same manner springs 73 and 82 open the line drop circuit at key B, and springs 81 and 82 at the same key open the supervisory circuit. Movement of key B opens the operators listening circuit between the springs 52 and 58, while movement of key B efiects the sameresult of preventing a report in the operators receiver by short circuiting the operators jack through the springs 97 and 98 and the conductors connected therewith.

A resistance coil 107 interposed in a conductor 106 placed across the two limbs of the circuit at the generator permits a leakage across and over the external circuit during the time main impulses are passing through the selector and neutralizes residual magnetism.

I claim as my invention:

1. In a telephone switch board system, the combination of a plurality of connection jacks, a plurality of connecting cords, correspending keys controlling the same, each cord key having two sets of contact springs and corresponding positions of the key, local circuit connections and a source of ringing current connected with one set of'spring contacts of each cord key, a master-key set and local circuit connections connecting the second set of contact springs of each cordkey with said master-key set, an operato-rs set and circuit connections placing said set in listening connection with the respective cord keys when the latter are shifted into position to close circuit with the master-key set, spring contacts, suitable circuit connections and a source of special current controlled by said master-key set, whereby said special current may be extended to any connecting cord through said master-key set and the corresponding cord key.

2. In a telephone switch board system, the combination with a plurality of connecting jacks, a plurality of connecting cords, and corresponding cord keys controlling the connecting cords, of a source of alternating current and suitable currentconnections between each cord and said source of alternating current, a source of unidirectional pulsating current, a master-key set connected with and controlling said latter source of current, circuit connections between said master key set and each of the cord keys and mechanism operating automatically for reversing the polarity of said uni-directional current.

3. In a telephone switch board system, the combination with a plurality of connecting jacks, a plurality of connecting cords, and corresponding cord keys controlling the connecting cords, of a source of alternating current and suitable current connections between each cord and said source of alternating current, a source of uni-directional pulsating current, a master-key set connected with and controlling said latter source of current, circuit connections between said master-key set and each of the cord keys, means for reversing the polarity of said unidirectional current and an electrically actuated circuit reversing device connected in circuit with said source of uni-directional 4. In a telephone switch board system, the Combination with a plurality of connecting jacks, a plurality of connecting cords, and corresponding cord keys controlling the connecting cords, of a source of alternating current and suitable current connections between each cord and said source of alternating current, a source of uni-directional pulsating current, a master-key set connected with and controlling said latter source of current, circuit connections between said master-key set and each of the cord keys, means for manually reversing the polarity of said unidirectional current and means for automatically reversing said current.

5. In a telephone switchboard system, the combination of a plurality of connecting jacks and a plurality of connecting cords and corresponding cord keys, a master-key set, circuit connections between said masterkey set and the several cord keys, a battery, a constantly running generator D, circuit connections connecting the generator with the master-key set, circuit connections connecting the battery with the master-key set and subsidiary contact devices controlled by the master-key mechanism and operating to open the circuit between the master-key set and battery when the generator circuit is closed and vice versa to open the circuit between the generator and master-key when the battery circuit is closed.

6. In a telephone switch board, a plurality of cord pairs and a key for each cord pair, each cord key having a self retaining position, a master-key-controlled group of instrumentalities for performing various line operations, and two sets of trunks multiply connected with the contacts of the several cord keys controlled by the self retaining position of the latter, said two sets of trunks leading to, and controlled by, the respective opposite sides of the master key, whereby external line operations may be performed on lines connected with either end ofthe original cord through the corresponding sides of the master key.

7. In a telephone switchboard system, the combination with a plurality of connecting jacks, a plurality of connecting cords, a source of uni-directional pulsating current, a master-key set connected with and controlling said source of current, circuit connections between said master-key set and each of said cord keys, and means external of said master-key set operating to automatically reverse the polarity of said unidirectional current.

8. In a telephone switchboard system, the combination witha plurality of connecting jacks, a plurality of connecting cords, corresponding cord keys controlling the connecting cords, a source of uni-directional pulsating current, a master-key set connected with and controlling said latter source of current,

circuit connections between said master-key set and each of the cord-keys, means for reversing the polarity of said uni-directional current, and an alternately actuated circuit reversing device connected in circuit with said source of uni-directional pulsating current, whereby the polarity of said current is automatically reversed at the end of a predetermined number of pulsations.

9. In a telephone switchboard system, the combination with a plurality of connecting jacks, a plurality of connecting cords, and corresponding cord keys controlling the connecting cords, of a source of uni-directional pulsating current, a master-key set connected with and controlling said source of current, circuit connections between said master key set and each of the cord keys, means for manually reversing the polarity of said unidirectional current, and means for automatically reversing said current.

10. In a telephone switchboard, a plurality of cord pairs and a key for each cord pair, a master'-key-controlled group of instrumentalities for performing various line operations, of two sets of trunks multiply connected with the contacts of the several cord keys controlled by the latter, said two sets of trunks leading to, and controlled by the respective opposite sides of the master-key whereby external line operations may be performed on lines connected with either end of the original cord through the corresponding sides of the master-key.

11. In a telephone switchboard, a plurality of cord pairs, and a key for each pair, a master-key set for performing various line operations, two trunk lines connected with the several cord keys, said trunk lines leading respectively to the opposite sides of the master-key, said master key embracing means for operatively associating itself exclusively with either end of each cord key, and an operators telephone set associated with said master key.

12. In a telephone switchboard, aplurality of cord pairs, a cord key for each pair constructed to have a self retaining closed position, a master key set, two trunk lines, contact devices controlled by the respective cord keys for connecting either trunk line to the corresponding end of such cord pair, said trunk lines being connected to the master key set, and contacts and suitable circuit connections controlled by said master key mechanism whereby current may be sent over either of said trunk lines to a corresponding end of a connected cord key independently of the other end thereof, a suitable source of current, and an operators telephone set normally connected with the master key set whereby it is brought into circuit whenever a cord key is operated to extend circuit to the master key. 1

13. In a telephone switchboard, a plurality of cord pairs and a key for each pair, two trunk lines common to the cord pairs, contact devices controlled by the respective cord keys for connecting the trunk lines to either end of the respective cord pairs, a source of current, a master key set, and circuit connect-ions whereby current may be sent over either of said trunk lines independently of the other, and an operators telephone set connected to the master-key set.

14. In a telephone switchboard, a master key set, a plurality of cord pairs, a key for each pair, a normally open talking circuit extending between the respective ends of each cord pair, an extension talking circuit connected in parallel with each of the cord keys and leading to a master key set, and contact devices associated with each cord key controlling by the same movement said normally open talking circuit and said eX- tension master key circuit whereby shifting of any cord key in a given direction closes. its normally open talking circuit and extends the same to the master key set.

HOMER J. ROBERTS. Witnesses:

E. E. CRAIG, J. F. BOYER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

